I was at Richard’s community garden at Ivory Heights with Kate last Tuesday where I spotted a watermelon vine growing in one of the plots in the vegetable section. The vine was just starting to flower and there were a couple of cheerful yellow flowers in bloom near the tip of the vine.
The watermelon vine has lobated leaves instead of the usual almost cordate leaves that many other cucurbits have. The ancestor of today’s watermelon was said to have originated from the African desert. No wonder there is a saying that watermelons need to grown in sandy, well-drained soils! They seem to be able to tolerate some degree of drought too. They need to be grown in full direct sunshine for best results!
Unlike the large round fruits we often see, the flowers of the watermelon are quite small in fact, the diameter of each blossom was at most 2 cm across! Due to the rather small size of the flowers, they can be quite hard to see and find as they can get obscured by the large green leaves.
The male flowers, like the male flowers of other cucurbits, are devoid of any prominent baby fruit below the petals. They usually produced in abundance compared to the number of female flowers.
The female flower, on the other hand, has a prominent baby fruit below the petals, which makes it easy to differentiate from the male flowers. It is interesting to see that the young ovary below the petals are quite hairy! It even has the green stripes we see on the watermelon fruit!
In an organically-grown garden, watermelon flowers will have the necessary wildlife around to help with their pollination. Excessive use of chemical pesticides can kill off beneficial wildlife which are not only needed to help with pollination of flowers but will also eradicate pedatory ones that help to keep undesirable pest population in check.
If one notices poor fruit set in the garden despite the appearance of numerous female flowers, then it may be time for one to try hand-pollination of the female flowers. The procedure is pretty simple. One just has to go pick a male flower, strip off all its petals to reveal its pollen laden anthers and then brush the anthers against the center of a female flower where the pistil is located. One male flower can be used to pollinate several other female flowers.
It can be difficult to tell whether watermelon flowers are pollinated properly since all of them will have the petals closing up and shrivelling away after a day. One probably has to wait for a week or two and patiently watch the development of the fruit. As long as the ovary does not turn yellow and continues to swell at a rapid pace, the fruit is then on its way to become a mature, juicy watermelon!
Richard’s fellow gardener grows the watermelon on top of a trellis so as to prevent the fruits from touching the ground. He told me the base of their previous watermelon fruit was disfigured with brown marks. It appeared as if some creature tried to chew away parts of the rind surface. I reckoned that could have been caused by snails or slugs that roamed the garden when the weather was wet and rainy.